Cleanups and "DLC"

I wasn't very happy with my map tiles, so I had the "brilliant" idea to update the tile image and offer it as "DLC". Unfortunately for me, uploads for a game are disabled until the judging is complete... Makes sense!

However, it's been interesting to go through the game with the pressure off. I've showed it to some friends and each time, new bugs are discovered and new features suggest themselves. One thing I got working was a way to preview the unit you were about to drop when building. I also reworked the way costs are computed a bit. While I was at it, I added a little animation for water tiles. Not very scalable, but it works for simple stuff.

Another thing that I've been thinking about is ways to smooth out the gameplay to make it more fluid. I wanted to have "events" (disasters, decisions and so on) in the original design, and opening things out so they're not specifically tied to the season change could make the experience better.

And... I also finally got a built executable working on the Mac! The secret in Racket is to use the Runtime Path stuff. This packages the texture file in properly with the executable. On PC it means that I don't have to crack open the produced zip file to add the image resources, on Mac it means that it works at all!